Power bank



FIG. 1 is a front elevational view of a power bank showing our new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof;

FIG. 7 is a first perspective view thereof; and,

FIG. 8 is a second perspective view thereof.

The broken lines in the drawings illustrate portions of the power bank which form no part of the claimed design.

The diagonal lines indicate transparency. 

CLAIM The ornamental design for a power bank, as shown and described. 